Fracking shakes up the Earth

By GEOFF ABERS, Commentary

Published 9:32 pm, Wednesday, January 16, 2013

In the debate over the environmental risks tied to hydraulic fracturing, the state has overlooked one threat that could give New Yorkers a jolt: the potential for wastewater disposal to trigger earthquakes.

New York sits on massive natural gas reserves trapped in shale rock underground. To extract that gas, energy companies cycle a mix of fluids underground under pressure in a technique called hydraulic fracturing. The main risk of earthquakes comes not from the fracking process itself, but from the disposal of millions of gallons of wastewater which are often pumped back even deeper underground. Recent rises in the practice of wastewater injection have coincided with a surge of earthquakes in relatively quiet parts of the country over the last four years, as detailed in a 2012 National Academy of Sciences report.

New York is in the process of writing rules to protect the environment in the event that hydraulic fracturing is allowed. However, while the state's draft environmental impact statement mentions the potential for the fracking process to trigger small earthquakes, it fails to address the more substantial risk of earthquakes triggered by subsequent deep wastewater injection. The state Department of Environmental Conservation claims that (see response No. 5946) deep well injection poses "essentially no increased risk to the public, infrastructure or natural resources from induced seismicity." But peer-reviewed research conflicts with the state's assurances.

Research findings presented in 2012 by our group and others have linked earthquakes in Arkansas, Oklahoma, Ohio, Texas, and Colorado to nearby waste disposal wells. In several cases, the fault ruptured into the same layer of rock where the waste had been injected, with some aftershocks traced to within a few hundred yards of injection wells. The largest, a magnitude 5.7, in Prague, Okla., on Nov. 5, 2011, was felt in 17 states and caused damage to nearly 200 homes and businesses, and destroyed at least 14 homes.

Around the same time, a series of earthquakes in Youngstown, Ohio, culminated with a magnitude 4.0 temblor, triggered by a relatively small volume of waste fluid injection. The well has since been shut down and the state has tightened its waste disposal regulations. Many of these developments occurred after New York released its draft environmental impact statement in September 2011.

Advances in fracking technology have boosted natural gas supplies in the U.S., reducing energy prices and the country's dependence on foreign oil. Clearly, fracking brings great benefits. However, disposing of the large volumes of water pumped into rock formations, laced with artificial and natural contaminants, remains a major problem.

Over the course of its lifetime, a production well can generate millions of gallons of contaminated water. The options for getting rid of this waste include storing it in pits, trucking it to other states or filtering it through public wastewater treatment systems. New York has indicated that open pits will not be allowed, and both trucking and treatment facilities have major environmental barriers.

As fluids are pumped into deep rock formations or the underlying bedrock, water pressure in rock pores increases, weakening the rock. If the well sits near a fault, the increase in fluid pressure can trigger earthquakes.

The risks of sending large amounts of fluid underground has been known since the 1960s, when a large-scale waste disposal operation on an Army base just outside Denver triggered a series of magnitude 4 to magnitude 5.5 earthquakes. The details, however, remain poorly understood. Thousands of injection wells have not produced earthquakes, though careful monitoring is rare. Scientists are trying to understand this.

It is important to recognize as well that manmade earthquakes are not included in published seismic hazard maps, which consider natural seismicity only. This means building codes and other measures to protect infrastructure are not taking into account the very real risk of manmade earthquakes.

The rise of fracking in the U.S., along with injection wells to dispose of the waste, warrants careful scrutiny by regulators in New York. Triggered earthquakes are only one of many concerns related to fracking, but a risk that must nonetheless be included in any thorough environmental risk assessment.